Venus Williams has reached the finals of the Australian Open and Wimbledon in 2017.
Photograph: Tim Ireland/AP

It is hard to underestimate someone with seven grand slam and 49 WTA singles titles. But despite this, Venus Williams’ remarkable run at Wimbledon is a surprise not just because of her age – at 37 Williams was the oldest finalist since Martina Navratilova – but because her battle with a chronic health condition nearly forced her out of tennis.

Diagnosed with Sjogren’s syndrome, an auto-immune disease whose symptoms include joint pain and fatigue, Williams has struggled in the demanding two week grand slam events since her diagnosis, pulling out of the 2011 US Open after being overwhelmed with fatigue and not reaching a quarter-final in singles at a grand slam tournament in 2012, 2013 or 2014.

So how, at an age when most players are long since retired, has Williams enjoyed one of the best years of her career, reaching two grand slam finals (before January’s Australian Open, she had not reached a final at a major since 2009)? One of the most significant reasons lies close to home: the absence of her sister – and the world’s best female player – Serena, who is expecting her first child. But when it comes to Venus herself, it’s hard to say that her physical gifts have eroded with time: playing in the two-week grand slam events involves a much greater workload than a regular one-week tournament if you are to make the final.

“Grand slams require maintaining peak level performance in all aspects over a longer period of time,” says Kathleen Stroia, senior vice president of sport sciences and medicine for the Women’s Tennis Association, “maintaining this for two weeks requires focus and sustainability at the highest level of play. Which is why it is so challenging and such an tremendous accomplishment to be a grand slam champion.”

Stroia maintains that veteran players, lacking the fresh legs of their younger opponents, have to use experience to their advantage. “Experienced players know the surface, the atmosphere, the culture and the ambience of the event,” she says.

Tired legs may have in fact played a part in Venus’ loss to Garbiñe Muguruza in the Wimbledon final on Saturday. But in her earlier matches, Venus was able to conserve energy with shorter points. In her semi-final and quarter-final matches she went out aggressively, and shorter points meant less distance to cover (22 and 20 feet per point respectively). However, in the final, Venus covered a third more distance per point (31 feet per point). Given her past struggles with fatigue, it may explain why Muguruza was able to easily win the second set after a hard fought first.

Of course, in many ways, after Sjogren’s syndrome robbed her of several years of her career, it’s a victory simply for Venus to be competitive again in tennis. As she told Health Magazine in January of this year, her newfound energy is in large part due to a radical change in her diet.

She now adheres to a raw vegan diet, one that eliminates all animal products — including dairy, meat, and fish — and anything cooked at high temperature. Venus credits the diet for the return of her endurance and strength. “I literally couldn’t play tennis anymore, so it really changed my life,” Williams said. “Thankfully, I was able to find something that helped me get back to doing what I loved.”

Diet and nutrition aside, the image of the tennis champion as willowy and slight is a vision of the past. “Now, the physical part is as important as technique,” says Nick Bollettieri, the International Tennis Hall of Fame coach to Andre Agassi, Jim Courier and the Williams sisters. As tennis has evolved, it has been transformed into less of a young person’s game, as top-level performance requires strength and physical maturity. “A lot of youngsters would struggle if they turned pro at 17 or 18, because the game is so physical,” he adds.

And then there’s the experience that years on the tour bring – Williams turned pro at the age of 14 in 1994, when Muguruza was three weeks old. Today, Williams is a player who has kept many of the physical gifts of her early career — witness her 118mph serve, clocked at the fifth highest of the tournament — combined with the wisdom of a veteran. Experienced players like Venus understand what they can do offensively and defensively, and play to these strengths. In a game of angles, especially on a fast surface like grass, the experienced player can use this to maximize the court.

As an example, in her semi-final against Johanna Konta, displaying confidence and power, Williams unleashed a soul-crushing serve straight at the Konta’s body to win a crucial break point, the equivalent of a dunk and stare down in the NBA.

Maintaining that Venus is in great shape physically, Bollettieri believes that one of Venus’ (and Serena’s) strengths is derived from a maxim repeated by her father when they were young players. “The ball is never out,” was a call to run down every drop shot, volley and lob, regardless of where it was placed on the court. While Venus may no longer have the mobility to chase down every ball, her father’s advice speaks to a mentally tough mindset as well.

While it has been easy to watch the power of Venus’ serve, admire her well placed forehands and marvel at her physical presence, it’s those intangible aspects that have perhaps taken her so far in 2017. Something that is not lost on Stroia: “She is a professional in every aspect; the way she prepares, the way she trains, who she trains with, the way she studies her opponent, the way she strategies; simply put, she’s a professional.”

Because of that, Stroia isn’t surprised about Venus’ success at this year’s Wimbledon. “Her experience on the big stage, experience playing in finals, the fact that she has won numerous grand slam titles all lend to her steadfast results.”

Bollettieri is quick to remind us that the world once thought Richard Williams crazy. “Richard introduced me to the girls when they were nine or 10 and told me they were going to be bigger than Michael Jordan.” Though where the Williams sisters belong in the pantheon of great athletes is yet to be determined, one thing now seems certain, we haven’t seen the last of Venus Williams.